There have been a number of proposals for preparation of combinatorial chemistry “chips” for performing assays such as DNA assays. In the case of DNA chips these have a number of defined features, DNA oligomers for instance, on their surface which are formed, by a number of different processes. When a sample including DNA fragments is passed over the surface of the chip, where DNA hybridisation occurs, which can be located by use of a suitable fluorescing compound on the DNA fragments, the type of DNA may be ascertained. These techniques may be used to determine the types of DNA that may be present in the DNA sample.
There can be problems, however, with addressing all the features on an assay chip and also problems synthesising the features, such as the DNA oligomers, on the various assay chip and it is to providing a substrate upon which features, such as DNA oligomers, can be synthesised that the present invention is directed.
In its broadest form the invention relates to the spatially defined deposition of any of a wide variety of chemical substances onto a disc surface and to discs having such surfaces. Substances may include, but are not limited to, coloured materials, dyes, drug molecules, polymers, catalysts, anti-wetting agents, pigments, etching chemicals, layerings and reagents for de-blocking, blocking, derivatisation and activation of solid phase chemical groups. Arrays can include deoxyribonucleic acids (DNA), peptides, peptidenucleic acids (PNA), ribonucleic acids (RNA) and other solid phase chemical arrays and arrays assembled by combinatorial chemistry.
The invention will be generally discussed in relation to its application to biochemical assay of biological samples such as DNA fragments but the invention is not so limited but can extend to other forms of combinatorial chemistry that can be carried out on a assay disc. This biochemical application invention will be mainly discussed in relation to DNA but the invention is not so limited but can extend to other peptides, peptidenucleic acids (PNA), ribonucleic acids (RNA) and other solid phase biochemical arrays.
Optical disc technology is well understood and suitable technology is available for writing and reading optical discs. An optical disc essentially consists of a substantially planar disc with a data surface moulded into a transparent material within the disc and which can be read using a suitable laser technique which tracks a spiral of pits on the data surface. The term data surface is used in this specification to describe such a spiral of data bits on a suitable disc format.
The optical disc format may be a compact disc (CD), a digital video disc (DVD) or nanometer (blue light readable) disc (Blu Ray™). The difference relates to the number of data bits which can be placed on a disc and the spacing and size of those data bits. Reading can be achieved by use of a laser of a selected wavelength which can give different data densities. The shorter wavelengths allow higher pit densities for reading and writing.